I would suggest this workflow:
have the volunteer form app sent to the freescout email address
use this setting: manage > settings > general > emails to customers > conversation history > do not include previous messages
use this setting: mailbox settings > edit mailbox > aliases > allow to reply from aliases (also, add all staff emails separated by a comma ex: user1@email.com,user2@email.com, etc.)
in your user profile settings > see screenshot below for settings that I use. I get a copy of the emails on my phone so I can reply when I'm on the go.
image.png
my customer don't see any ticket numbers and I can reply from my phone without having previous convos show up in the replies. I would recommend setting up an auto-reply in the mailbox settings, so customers know their message was received and when to expect a reply back.